Research On The Effects Of Value Parameters Of Gasoline Engine At Low Speed

Nowadays, traffic in the city is more and more crowded. And so for most automobiles, run slowly at most driving time. In order to ensure enough power while driving, it is very important to improve the torque at low engine speed. In this paper, the valve timing was optimized and the new cam profiles were designed to achieve the target of improving the low-speed torque on a 2.0L gasoline engine.Firstly, Timing Drive was used to design the cam profile for the target engine. And then, the influence of changing the valve timing the parameters of the cam profile and the ramp on the radius of curvature, the fullness ratio and the maximum acceleration were analyzed. So the selection and design suggestion of some parameters can be gotten correctly. For example in an appropriate period of speed range the fullness coefficient and minimum radius of curvature of CAM contour line is increased but the maximum acceleration is decreased along with the buffer period of speed increase.Meanwhile,the software GT/Power was used to build the simulation model of naturally inspired 2.0L gasoline engine. The parameters of reasonable import and valve train were led into engine model, the reasonable division of air intake system was done, and then an engine simulation model was established. Then comparison of the Brake Specific Fuel Consumption and the Brake Torque between the simulation and the experimental results were made to verify the accuracy of the simulation model. The Error was controlled within 5%.Finally, the software AVL Timing Drive was used again to design the cam profiles of each group of valve timing. The effect of valve timing on the engine torque at low speed was studied. Some design solutions suitable for different speed increase torque were gotten, finally the optimized cam plan which can improve the low speed torque was confirmed. Of the torque at low speed increase is about 5.5% to meet the target requirements.